Cerebral function and muscle afferent activity following intravenous succinylcholine in dogs anesthetized with halothane: the effects of pretreatment with a defasciculating dose of pancuronium.

The effects of iv succinylcholine (SCh) on cerebral blood flow (CBF), muscle afferent activity (MAA), electromyographic activity (EMG), visible fasciculations, and PaCO2 were tested in 12 dogs anesthetized with 0.87% end-expired halothane (1 MAC). Six dogs (group I) received treatments of both SCh 1.0 mg/kg iv and saline placebo 3.0 ml iv. Fasciculations and substantial increases in EMG activity were observed in all six dogs given SCh. At the onset of fasciculations, there were parallel increases in MAA and CBF to peak values of 466% +/- 77% of control (mean +/- SE) and 136% +/- 5% of control, respectively, at the 1-min measurement point. Thereafter, both MAA and CBF declined toward control values. An additional six dogs (group II) were prepared as above; however, they were pretreated with a defasciculating dose of pancuronium 0.01 mg/kg iv 5 min before being given SCh 1.0 mg/kg. These dogs were also given treatments of saline placebo 3.0 ml iv during another portion of the study. None of these six dogs had visible fasciculations following SCh, and only in one was slight EMG activity detected. Following iv SCh, there were parallel increases in both MAA and CBF. The peak MAA value of 255% +/- 56% of control occurred at the 1-min measurement point and was followed by a gradual decline in MAA. CBF increases were greatest during the periods of greatest MAA (i.e., the 1- to 3-min measurement points). The largest increase in CBF (128% +/- 9% of control) occurred at the 3-min measurement point.(ABSTRACT TRUNCATED AT 250 WORDS)